1. Field of the Invention
The present invention relates to an office machine that performs a specific operation of transferring paper sheets, and more particularly, to a paper transferring mechanism of an office machine to perform a specific operation of transferring paper sheets and a controlling method thereof.
2. Description of the Related Art
In general, office machines perform a specific operation of transferring paper sheets, reading information indicated on the paper sheets and transmitting or copying the read information. Facsimiles machines, copying machines, multi-function machines, etc., are examples of such office machines.
FIG. 1 is a view of a sheet transferring mechanism in a facsimile machines to show an example of an office machine to perform a specific operation of transferring paper sheets.
Referring to FIG. 1, the sheet transferring mechanism includes a drive gear 1, an Automatic Document Feeder (ADF) gear train 10, a feed gear train 20, a discharge gear train 30, and first and second sensors 41 and 42.
The drive gear 1 is coupled with a rotation shaft of a motor (not shown) while being meshed into an intermediate gear 3. The intermediate gear 3 is in the form of a double gear including two coaxially connected gears 4 and 5, which have different diameters of pitch circles.
The ADF gear train 10 includes an ADF gear 11 coaxially coupled with an ADF roller (not shown) and an ADF step gear 13. The ADF roller separately picks up the paper sheets stacked in a paper cassette (not shown) one by one and transfers each paper sheet toward a feed roller (not shown). The ADF step gear 13 at one side is meshed into the ADF gear 11 and at the other side meshed with the gears 4 and 5 of the intermediate gear 3.
The feed gear train 20 includes a feed gear 21 coaxially coupled with the feed roller and a feed end gear 23. The feed roller transfers the paper sheet, which is picked up by the ADF roller and transferred along a sheet course A, toward a scan unit 45. The feed end gear 23 is meshed at one side into the feed gear 21 and at the other side with the gears 4 and 5 of the intermediate gear 3.
The discharge gear train 30 includes a discharge gear 31, a first intermediate gear 33, a second intermediate gear 35 and a discharge end gear 36. The discharge gear 31 is coaxially coupled with a discharge roller (not shown) to discharge a sheet that is completely scanned. The first intermediate gear 33 and the second intermediate gear 35 are installed between the discharge gear 31 and the discharge end gear 36, and transmit a rotational force of the discharge end gear 36 into the discharge gear 31. The discharge end gear 36 is meshed at one side into the intermediate gear 3 and at the other side into the second intermediate gear 35.
The first sensor 41 is disposed in front of the feed roller on the sheet course A between the feed roller and the ADF roller to detect any sheet fed from the ADF roller. The second sensor 42 is disposed in the back of the feed roller on the sheet course A between the feed roller and the discharge roller to confirm whether the sheet past through the feed roller has been scanned or not.
Hereinafter, an operation of the sheet transferring mechanism as set forth above will be described in reference to FIG. 1.
When the drive gear 1 is rotated with the motor, the intermediate gear 3 meshed into the drive gear 1 is also rotated. The rotation of the intermediate gear 3 is transmitted into the ADF roller via the ADF gear train 10 meshed into the intermediate gear 3. That is, the rotational force of the motor is transmitted into the ADF gear 11 via the ADF step gear 13 meshed into the intermediate gear 3, causing the ADF roller coaxially coupled with the ADF gear 11 to rotate. The ADF roller rotates in a direction reverse to a rotation direction of the motor.
The feed gear train 20 and the discharge gear train 30 are also rotated. In the feed gear train 20, the feed gear 21 is rotated via the feed end gear 23 meshed into the intermediate gear 3, causing the feed roller coaxially coupled with the feed gear to rotate. The feed roller rotates in a direction reverse to the rotation direction of the motor.
In the discharge gear train 30, the discharge gear 31 is rotated via the discharge end gear 36 meshed into the intermediate gear 3 and the second intermediate gears 33 and 35 meshed into the discharge end gear 36, causing the discharge roller coaxially coupled with the discharge gear 31 to rotate. The discharge roller rotates in a direction reverse to the rotation direction of the motor.
Therefore, as the motor rotates clockwise, the ADF roller is rotated counterclockwise to pick up one of the sheets from its stacked position in the paper cassette and to displace the same toward the feed roller, which is also rotated counterclockwise along with discharge roller.
When the paper sheet transferred by the ADF roller activates the first sensor 41, the motor rotates counterclockwise. Accordingly, the feed roller is then rotated clockwise to transfer the paper sheet from the ADF roller toward the scan unit 45 disposed in the back of the feed roller. After passing over the scan unit 45 by the feed roller, the paper sheet is discharged out by the discharge roller which, at this time, is in a clockwise rotation like the feed roller. When a given time period lapses after the second sensor 42 detects the end of the paper sheet being transferred toward the scan unit 45, the motor rotates clockwise so that the ADF roller picks up another paper sheet from the paper cassette again. The above process allows information of the paper sheets stacked in the paper cassette to be read and successively transmitted or copied.
However, the above conventional paper transferring mechanism has a construction in that the feed roller and the discharge roller change rotation direction when the motor changes rotation direction, so that a new paper sheet may be picked up only after a previous one is completely discharged via the discharge roller. Accordingly, a pick-up interval between two adjacent paper sheets increases, prolonging time for facsimile transmission while reducing a number of paper sheets to be copied or scanned per minute.